3 - Leverage intrinsic motivation, not extrinsic. In short, bribery is not sustainable. Badges and points are nonsense, "gamification" is nonsense. Notice that newspapers have crossword puzzles and sudokus, and no bribery is involved - these activities are intrinsically fun.

4a - Focus on the fence-sitters. Target those people for whom embracing critical thinking is a small step, not a huge leap.

4b - Use Aikido, not boxing. Most people don't learn when confronted, sneak memes in through the side door.